I've long maintained that the philosophy-inclined person is naturally likely to feel an affinity with the Greeks and Romans. After all, they gave us the blueprint for closeness and intimacy, things on which our enculturation rests.
The first time I heard of Derrida's work on friendship and politics was over a quick, friendly chat with one of my dissertation committee members. He said, jokingly, that one could expect anything from Literary Theory these days. Derrida, the pater of deconstruction, was working on friendship in the twilight of his years. I said that I wasn't all that surprised that he would choose to dedicate the last years of his research life to such a pursuit.
What else do we preoccupy ourselves with, anyway? Even the least attached of people, is consumed with thoughts of attachment. The latter looks different in different people. Whether we attach to people or the results of associations with people and/or sources of interest, human beings are burdened with the concern of attachment as we simply cannot survive on our own. Plato, by way of Aristophanes, tells us of the cravings we have to feel more empowered and less choppy and how they're rooted in our choppy natures. Our inadequacy, which often feels to be emotional and mental, is very much physical, according to him. Zeus and the gods chopped us up, says Aristophanes, and, as a result, we're perpetually looking for the missing parts so that we can fit again. Metaphorically, the more valid point that the Greeks were making is that association, or sociality at large, is not a matter of choice for most who choose to live, and live well, in society. Sociality is a matter of necessity.
True simbiosis is rarely present. Faux simbiosis, however, is the very cradle of sociality. Fake things are not always problematic, however. Nietzsche talks of collective lying and the decisions we've made to believe it as truth for the sake of living. The pretense of the real thing seems to become in time the thing itself. And therein lies the importance of such notions as friendship, attachment, loyalty of sociality, et al. Such tenets are important to civilized society as they are the unspoken agreement on which various channels support themselves.
In my own 398-page musings on literature and philosophy in the Middle Ages, I explored the concept of medieval friendship at length. Granted, I mostly wrote about its function and utility but, as much of the Western canon shows, we cannot comment on our culture and civilization without tipping the hat to the work of Plato and co., on the matter.
Many view Derrida's work in the twilight of his life as less substantial than his monumental contribution to Literary Theory i.e. Deconstruction I mean, the number of faculty hired as practitioners of his theory alone is enough to worship at his altar. At least, till tenure.
Derrida's musings on friendship are not novel, however. They're very much imitative of the Greeks. Plato's Symposium after all is nothing if not a collection of chats with friends over wine. In vino vertias as later on, their friends to the North would say.
You can read the rest of Derrida's comments on politics and friendship here. Below is a snippet from it:
"... the friendship grounded on utility and usefulness, and this is political friendship ... and on the lower level, friendship grounded on pleasure - looking for pleasure among young people, Aristotle says. So you see that we have a concept of friendship which is and is not political. The political friendship is one kind of friendship ... So, there are a number of problems in which you see love - not love, but philia or friendship playing an organising role in the definition of the political experience."